Significance Cold caustic extraction (i.e., CCE) is widely used in mill practice for hemicelluloses removal, and the parameters of which can significantly affect the hemicelluloses dissolution. Therefore, the dissolution behaviors of hemicelluloses under different CCE process parameters have been investigated. The results showed that with the temperature increases, the dissolution of hemicelluloses also increases. However, the effect of alkali content showed complicated, since lower content (<9.0 wt %) was good for the swelling of fibers (i.e., good for hemicelluloses dissolution), but higher content (>9.0 wt %) would accelerate the competing hydration of sodium ions with water and thus limited the dissolution of hemicelluloses. Besides, a mathematical model has been also developed for predicting the hemicelluloses dissolution during CCE process, which can provide a good guidance for enhancing the purification efficiency in the CCE process operation. © 2018 American Institute of Chemical Engineers AIChE J, 65: 13–17, 2019